Thermoelectric couple



Sept. 18, 1923. 1,468,456

W. H. BRISTOL THERMOELECTRIC C UPL Filed Sept 14 1922 IN V EN TOR 4% ll dam [ff/1310! BY HIS ATTORNEYQ "WILLIAIFZ E. BRISTOL, F VIATERBURY, CONNECTICUT.

THEREZIOELECTRIC COUPLE.

Application filed September 14, 1922.

To all to 310m it may concern:

Be it known that l, lViLLLizu ll. Bmsron, a citizen o the United States, and a resident of llaterbury, in the county of New Haven and State of tonnecticut, have invented certain new and useful Improvements in The"- moelectrio Couples, of which the following is a specification.

The invention relates to thermoelectric couples, more particularly of the compound type as set forth in my prior l Letters atent :ttltlli'i'l, and in U. S. Letters Patent .#l.025.7l5. Couples of this type consist of an active or fire-end portion and an extension portion, the latter setting up at the junctions with the former secondary couples whose thermoelectric effects are arranged to neutralize each other. For example, a couple may consist of a tire-end portion of platinum and platinum rhodium joined at one end, the other end being connected with wires respectively of an alloy of copper and nickel and of copper. is set torth in Patent No, 1,025- 715, the wire. of copper alloy may vary from 95% to 99.9%- copper with to 0.10% nickel. Such s couple sets up an allowable volta e, for temperature variations at the cold end between 32 F. and 212 F., amounting to an average of 0.635 milli-volts. This voltage will not. however. seriously effeet the correctness of the reading of temperatures to which the tire-end of the couple is exposed, as the couples thus provided Wllll extension portions set up secondary couples, at the respective junctions of the extensions with. the fire-end portion, which substantially neutralize each other.

However, it has been found extremely difiicultto provide allov wire in lots of uni form composition; and. thereforegit is rendered' ditficult to hold the volta'e set up within the prescribed limit of 0x35 millivolts for the temperature variation noted. It is the ohiectof the present invention to so arrange the extension wire that this difiiculty is readily overcome and the desirable compensating or neutralizing effect attained. For example. instead of constructing the aly portion of the extension of a single wire of exactly the proper composition, the same is composed of a plurality of strands which differ as to their potential relative to the particular thermo-electric element of the fireend portion of the couple to which the stranded wire is joined. the strands being so selected, however, that their total effect will Serial No. 588,137.

set up substantially the desired neutralizing voltage.

In the accompanying drawin s, a couple has been illustrated embodying t 1e novel arrangement, Fig. 1 being an elevation thereof and Fig. 2 a transverse section taken on the line 2-2, Fig. 1..

As shown, the couple consists of the primary or fire-end and active portion composed of the two elements 1 and 2 joined at the one end and respectively of platinum and alloy of platinum and 10% rhodium. To the free end of this couple is connected the extension portion consisting of the elements 3 and 4 of an alloy of copper with nickel and of substantially pure copper, respectively. In accordance with the invention, the former is of stranded wire, the individual strands 5 of which have different potential values relatively to the element 1. The element 4 may. of course, also be of stranded wire, all the strands, however, being of substantially pure copper.

As a specific example, with one portion of the extension of copper, the other extension wire may be composed of alloy wire of seven strands iving, when joined to the primary couple e cnient, for the couple as whole, the following respective voltages over a variation of temperature from 32 F. to 212 F. at the cold end.

0.655 milli-volts.

The average of these compound couple voltages will be 0.635, which iswithin the prescribed limit.

Furthermore, if the other element. for example, copper, should not be substantially pure copper as required. and therefore alter the allowable voltage set up, this could be compensated for thru changing the voltage set up by the stranded portion of the extcnsion. the average voltage of same being made higher or lower as required by the condition of the copper extension portion.

In this manner, it becomes a comparatively simple matter to effectthe desired balance, and there is not required the extreme care otherwise necessary in preparing the alloy wire so that all batches shall run substantiali y uniformlyas to the percentage of alloying metal.

I cla1m:- v 1. An extension portion for compound 5 thermo-electric couples, consisting of a stranded wire, the individual strands of which have different couple.

2. A compound thermo-electric couple potential values in the :10 consisting of an active or fire-end portion and an extension portion joined thereto, one element of which is an alloy composed of stranded wire, the individual strands. of

WILLIAM H. BRISTOL. 

